Set the environment texture used for image based lighting.
This texture is supposed to represent the scene background. If it is not a cubemap, the texture is supposed to represent an equirectangular projection. If used with raytracing backends, the texture must be an equirectangular projection and must be constructed with a valid vtkImageData. Warning, this texture must be expressed in linear color space. If the texture is in sRGB color space, set the color flag on the texture or set the argument isSRGB to true.